Pilot study suggests Calgary PLUS may improve pleural effusion detection
Bottom line
A pilot study in the Journal of Small Animal Practice suggests that where clinicians place an ultrasound probe, and how they orient it, can meaningfully change how often pleural effusion is detected in dogs. In canine cadavers, the modified Calgary Pleural Space and Lung Ultrasound (Calgary PLUS) technique detected pleural effusion in 89.1% of scans, compared with 60.9% for a modified thoracic focused assessment with sonography for trauma, or TFAST, approach, with the biggest gap seen for smaller effusions, according to the study abstract. The work adds to a broader push in veterinary point-of-care ultrasound, or POCUS, toward more standardized thoracic scanning methods, especially as clinicians use ultrasound for rapid triage and procedural guidance. (pmc.ncbi.nlm.nih.gov)
Why it matters: For veterinary professionals, the takeaway is practical: a negative thoracic POCUS scan may reflect protocol limitations as much as true absence of fluid, particularly when effusions are small. That matters in emergency and critical care settings, where pleural effusion can change stabilization decisions, thoracocentesis planning, and whether a dyspneic patient is moved to radiography. Existing TFAST frameworks are well established for pleural and pericardial effusion detection, but recent literature has also highlighted variability across veterinary thoracic ultrasound techniques and the need for clearer anatomic standardization. (pubmed.ncbi.nlm.nih.gov)
What to watch: The next step is whether these cadaver findings are confirmed in live, spontaneously breathing dogs, and whether training programs or thoracic POCUS protocols shift toward Calgary PLUS-style scanning for small-volume pleural effusion detection. (pmc.ncbi.nlm.nih.gov)
Key facts
- Study type
- Pilot study
- Journal
- Journal of Small Animal Practice
- Species
- Canine cadavers
- Comparison
- Modified Calgary PLUS vs. modified TFAST
- Detection rate, Calgary PLUS
- 89.1% of scans
- Detection rate, modified TFAST
- 60.9% of scans
- Main finding
- Probe placement and orientation affected pleural effusion detection
- Best performance
- Smaller fluid volumes
A new pilot study in the Journal of Small Animal Practice points to a simple but important issue in veterinary point-of-care ultrasound: probe placement and orientation may substantially affect whether clinicians detect pleural effusion. In canine cadavers, the modified Calgary PLUS technique outperformed a modified TFAST approach, detecting pleural effusion in 89.1% of scans versus 60.9%, with the advantage most apparent for smaller fluid volumes, according to the published abstract. (pmc.ncbi.nlm.nih.gov)
That finding lands in the middle of a larger conversation in small animal emergency and critical care about standardization. TFAST is already a validated and widely taught thoracic POCUS framework for identifying pleural and pericardial effusion in dogs and cats, and it remains a core bedside tool in triage. At the same time, recent reviews have noted that veterinary thoracic ultrasound still suffers from inconsistent scanning methods and anatomical definitions, which can lead to variable results between protocols and operators. (pubmed.ncbi.nlm.nih.gov)
The study’s authors, C. Di Franco, J. Menard, A. Romero, S. Chalhoub, V. Madden, and S. R. Boysen, focused specifically on detection of pleural effusion in canine cadavers. While the full paper was not directly accessible in the search results, related conference material appears to describe a closely aligned cadaver pilot in which novice sonographers received brief training in TFAST, Vet-BLUE, and PLUS before scanning dogs for pleural fluid, underscoring the training-sensitive nature of these protocols. A later Journal of Small Animal Practice article on Vet BLUE also cites this 2020 pilot study, suggesting it has already informed subsequent work on thoracic ultrasound protocol performance in companion animals. (pmc.ncbi.nlm.nih.gov)
The Calgary PLUS approach has also been showing up in adjacent research and teaching from the University of Calgary group. A 2026 cadaver study on POCUS-guided thoracostomy tube placement used the Calgary PLUS protocol to identify preexisting pleural fluid or air, and training materials from the Calgary VPOCUS ecosystem position PLUS as part of a structured decision pathway for dogs presenting with respiratory distress. That doesn’t prove superiority in live clinical patients, but it does suggest the protocol is being integrated beyond a single pilot paper and into broader emergency workflow development. (onlinelibrary.wiley.com)
Independent expert reaction specific to this new paper was limited in open web results, but the surrounding literature helps frame the significance. Reviews of veterinary lung ultrasound emphasize that thoracic POCUS can rapidly identify pleural fluid with less stress than radiography in unstable patients, and pleural ultrasound is already considered especially useful when fluid volumes are small, loculated, or when thoracocentesis carries added risk. In other words, if one protocol is better at finding subtle effusions, that could translate into earlier recognition and safer intervention, particularly in emergency settings. (pmc.ncbi.nlm.nih.gov)
Why it matters: For veterinary teams, this study is less about replacing TFAST outright and more about understanding the limits of a given scan pattern. If modified Calgary PLUS is more sensitive for small-volume pleural effusion, clinicians may need to think more carefully about protocol choice when a patient’s respiratory signs are concerning but the initial thoracic scan is unrevealing. It also reinforces a broader operational point: POCUS findings depend not just on the machine and the operator, but on exactly where and how the probe is used. That has implications for staff training, protocol standardization, quality assurance, and communication with pet parents when explaining why repeat imaging or escalation may still be needed after a “negative” bedside scan. (pmc.ncbi.nlm.nih.gov)
There are also important caveats. This was a cadaver pilot study, so the results may not fully reflect live patients with spontaneous breathing, variable positioning, and real-world motion artifact. Related recent cadaver work from the same broader research area has made similar cautionary points, noting that image interpretation can be easier in frozen-thawed specimens than in live animals. That means the headline result is best viewed as a strong signal for protocol refinement, not a final answer for clinical practice. (pmc.ncbi.nlm.nih.gov)
What to watch: The key next step is prospective validation in live dogs, ideally across different operator experience levels and clinical settings. If those studies confirm better sensitivity for small effusions, veterinary educators, emergency services, and continuing education programs may begin adjusting thoracic POCUS teaching to emphasize Calgary PLUS-style landmarks and probe orientation alongside, or in some cases ahead of, traditional TFAST windows. (pmc.ncbi.nlm.nih.gov)